1. Field of the Invention
The invention relates generally to a Viterbi decoding apparatus and method thereof, and more particularly, to a Viterbi decoding apparatus with improved decoding ability and method thereof.
2. Description of the Related Art
FIG. 1 depicts a diagram of an optical disk system. In FIG. 1, the optical pickup unit 2 retrieves a radio frequency (RF) signal from an optical disk 1. The retrieved RF signal is sent to a signal processing unit 3 for further processing. The processed signal is provided to an analog-to-digital converter (ADC) 4 to be digitalized into a digital signal. The digital signal is sent to a phase loop lock (PLL) processing unit 5 and a finite impulse response (FIR) equalizer 6. The FIR equalizer 6 performs an equalization operation on the received signal and outputs an equalized signal to a Viterbi decoder 7 for data decoding. The Viterbi decoder 7 decodes the received signal and outputs a Viterbi-decoded signal (binary data). The binary data is decoded by a decoder 8 to output a decoded data.
Generally, modern optical disk systems have small channel bit lengths and track pitches, thus making data retrieval more difficult. In light of the problem, a Partial Response Maximum Likelihood (PRML) mechanism is applied in optical disk systems. However, performance of the optical disks applying the PRML mechanism is less than desired.